Kyanite, Sillimanite, and Andalusite Deposits of the Southeastern ...

INTRODUCTION
Corbett deposit near Smithfield, Johnston County, N.C.;
Cherokee and York Counties, S.C.; Little Mountain, Newberry
County, S.C.; and Graves Mountain, Ga. The principal
deposits of kyanite schist and gneiss described are in the
Burnsville-Swannanoa area, Buncombe, Yancey, and Mitchell
Counties, N.C., and in the Clarkesville district, Habersham
and Rabun Counties, Ga. The major deposits of sillimanite
schist described are in the Piedmont belt of North Carolina,
South Carolina, and Georgia and in the Blue Ridge of North
Carolina and Georgia. Andalusite-pyrophyllite-quartz deposits
described are at Bowlings Mountain, Hillsboro, Snow Camp,
and Staley, N.C., and at Brewer gold mine and Boles Mountain,
S.C.
INTRODUCTION
During the present century the aluminum silicate
minerals kyanite, sillimanite, and andalusite (each
with the same chemical composition Al2Si0 5 ) have
become industrially important in the manufacture
of various ceramic articles used at high temperatures.
Industrial application of the Al2Si0 5 minerals
followed the discovery during World War I
that the high-quality porcelain required in spark
plugs for airplane engines could be made from
material having this chemical composition. Various
other articles capable of withstanding the high temperatures
of different industrial processes have since
been developed. The Al2Si05 minerals and other
high-alumina substances are widely used now, principally
in the manufacture of refractory linings for
metallurgical and glass furnaces, boilers, and kilns.
Kyanite has been the principal Al2Si0 5 mineral
used because it has generally been found in higher
grade deposits than either andalusite or sillimanite.
The Al 2Si0 5 minerals consumed by the domestic
industry have come mainly from deposits in the
Southeastern States, California, and Nevada and
from ores imported from India, Keyna, and the
Union of South Africa. The entire domestic production
of these minerals since 1950 has consisted
of kyanite concentrates from two mines in Virginia
and one in South Carolina, and of andalusite contained
in pyrophyllite ore from some pyrophyllite
mines in North Carolina.
The imported kyanite is a crystalline aggregate
that forms a better bond in refractory bricks than
does the fine-grained domestic kyanite concentrate;
it has become known as strategic-grade kyanite because
it has been essential for certain purposes. The
lack of such high-quality kyanite in the United
States has stimulated interest in domestic deposits
during recent years. However, synthetic mullite is
now being made from domestic raw materials; this
product is as good as mullite made from imported
strategic-grade kyanite. This report presents the
results of an investigation by the Geological Survey,
from 1950 to 1953, of deposits of the Al2Si0 5 minerals
in the Southeastern States.
PREVIOUS STUDIES
Kyanite has been known for many years at
numerous localities in the metamorphic belt of the
Southeast, but only a few geologic studies were
made of these deposits before the development of
kyanite as an industrial mineral. The more important
of these studies were those of Graves Mountain,
Ga., by Watson and Watson (1912), in the Tate
quadrangle, Georgia, by Bay ley (1928), and in the
Gaffney and Kings Mountain quadrangles, North
Carolina-South Carolina, by Keith and Sterrett
(1931). Prospecting and mining of the deposits
began shortly after 1920, and many articles describing
the kyanite deposits and the mining operations
have since appeared. The principal papers are as
follows: Kyanite in Virginia by Jonas (1932) and
Watkins (1932), in North Carolina by Stuckey
(1932) and Chute (1944), in South Carolina by
L. L. Smith and Newcome (1951), and in Georgia
by R. W. Smith (1936), Prindle and others (1934),
and Furcron and Teague (1945). A general review
of kyanite and sillimanite deposits in the Southeast
has been given by Furcron (1950).
Sillimanite had been found at a few localities
many years ago, but it is only recently that it has
been recognized as widespread in the schists of
certain areas. The possibility that sillimanite might
be substituted for kyanite imported from India encouraged
the exploration of these deposits during
and since World War II. This work was carried on
mainly by the U.S. Bureau of Mines and by the
Tennessee Valley Authority in cooperation with the
geological surveys of the States of North Carolina,
South Carolina, and Georgia. Sillimanite deposits in
North Carolina have been described by Hunter and
White (1946) and Hash and Van Horn (1951), in
South Carolina by L. L. Smith (1945), Hudson
(1946), Hickman (1947), and Dosh (1950), and in
Georgia by Furcron and Teague (1945) and Hudson
(1946). General reviews of the sillimanite deposits
have been given by Teague (1950) and Furcron
(1950). The zone of sillimanitic rocks in South
Carolina and North Carolina has been discussed in
a paper on the geology of the inner Piedmont by
Overstreet and Griffitts (1955).
Andalusite was not known to occur in important
amounts in the region until it was discovered recently
to be associated with other high-alumina
minerals diaspore and topaz in several pyrophyl-